In this Nov. 20, 2014 photo, Deputy Robert J. Rudisill takes a prisoner though a body scan after being taken into custody at San Diego County sheriffs Vista Detention Center in Vista, Calif. The facility receives male and female inmates from all the cities in northern San Diego County. (AP Photo/Chris Carlson)

VISTA, Calif. (AP) – Drug smuggling is up at many California county jails and one reason, sheriff's officials say, is that some parolees are getting arrested just so they can try to sneak narcotics behind bars.

Sheriff's departments, which run county jails, report more illegal drugs in the three years since an overhaul of the state corrections system started sending lower-level felons to county lock-ups to reduce overcrowding in state prisons.

Officials say the "prison realignment" law generally has brought tougher inmates into jails and they point to a provision allowing parole violators to serve 10 days in the local jail instead of months in prison.

So-called "flash incarceration," intended to give authorities a way to avoid sending parolees back to state prisons, is being used by some offenders to bring drugs, hidden inside their bodies, into county jails, sheriff's officials say.

"These folks have brought with them prison politics, prison contraband, prison culture. It's very different than what the deputy sheriffs were previously used to dealing with," said Stanislaus County Sheriff Adam Christianson.

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"Nobody was ready for this freight train," said Christianson, president of the California State Sheriff's Association.

Franklin Zimring, a criminal justice expert at the University of California, Berkeley, is skeptical that realignment is entirely to blame for the problems, noting that sheriff's departments were among the law's most vocal opponents.

Local departments could be motivated to play up problems to get more money or to distract attention from their own difficulties implementing the law, he said. "All of a sudden the counties have skin in the game," Zimring said.

Illicit drugs in jails aren't new, and having inmates using and selling them makes it harder to keep order. Still, the volume and type — heroin, meth and cocaine — flowing into jails is jarring, sheriff's officials say.

In a common scenario, a former prison inmate will intentionally commit a minor infraction to get arrested and then smuggle drugs in by swallowing them in balloons so they will be missed by strip searches.

To catch these smugglers, San Diego County, for example, is among those now using body scanners.

A recent law enforcement bulletin warned of the smuggling trend and cited a case in which a parolee walked into a liquor store and began smashing bottles — a crime that was just enough to get him returned to jail for a short stay.

The flourishing drug trade — often controlled by gangs — has raised the potential for violence, with fights among inmates and assaults on deputies on the rise under realignment, sheriff's officials say.

Counties are not required to track drug seizures and there is no statewide data for jails.

To get a sense of the problem, The Associated Press surveyed the 10 most populous counties and found that since realignment, seven have seen significant increases in narcotics cases since 2011, the first full year of realignment.

San Diego, Orange, San Bernardino, Riverside, Los Angeles, Sacramento and Santa Clara counties all saw increases. Fresno and Contra Costa counties said they have not seen a noticeable uptick and Alameda County did not provide information.

Larger inmate populations in some counties since realignment don't account for the increase.

For example, San Bernardino has a court-ordered cap on its number of inmates and yet reported a 102 percent increase in drug seizures between 2010 and 2012, the most recent numbers available.

Counties are boosting security efforts to stop the flow of drugs. Los Angeles and San Diego counties have bought full-body scanners that give deputies a full view of the inmate's internal organs and any contraband they might be hiding.

Orange County, which saw drug cases jump from 91 to 378 in the past three years, is planning to buy several machines. Other jails elsewhere are increasing perimeter patrols and strip searches and adding drug-sniffing dogs.

In Los Angeles County, where the jails hold more than 18,000 inmates, officials estimate a 10 percent increase in drug smuggling cases and formed a special investigative team four months ago to address the problem.

The increased security measures mirror what already has happened in state prisons, where authorities have struggled for years to stem the flow of illicit drugs into 34 facilities.

State prison officials recently announced one of the nation's toughest anti-drug policies — including airport-style hand swabs and drug-sniffing dogs — after 430 pounds of drugs, mostly marijuana, was seized through September alone.

The reliance on scanners has alarmed inmates' rights advocates, who say that the measure ignores another potential source of drugs: corrupt deputies.

"If you're putting in scanners, are you going to apply them to everybody? I'd be shocked if they are," said Peter Eliasberg, legal director with the American Civil Liberties Union's Southern California branch.

During a recent weekday morning in San Diego, deputies, probation officers and immigration agents did not pass through the department's newly installed scanners but incoming inmates did.

A log book next to the scanner, which looked like an airport metal detector, showed in the past month deputies have found meth and a crack pipe on inmates and spotted possible drugs in the intestines or abdomens of seven more.

The jails installed the scanners in August after seeing their narcotics cases jump from 145 in 2011 to 335 so far this year, sheriff's Commander John Ingrassia said.